%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 2004-2016. All Rights Reserved.
%%
%% Licensed under the Apache License, Version 2.0 (the "License");
%% you may not use this file except in compliance with the License.
%% You may obtain a copy of the License at
%%
%% http://www.apache.org/licenses/LICENSE-2.0
%%
%% Unless required by applicable law or agreed to in writing, software
%% distributed under the License is distributed on an "AS IS" BASIS,
%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
%% See the License for the specific language governing permissions and
%% limitations under the License.
%%
%% %CopyrightEnd%
%%
%%% @doc Common Test Framework test execution control module.
%%%
%%% <p>This module is a proxy for calling and handling locks in
%%% common test hooks.</p>
-module(ct_hooks_lock).
-behaviour(gen_server).
%% API
-export([start/1, stop/1, request/0, release/0]).
%% gen_server callbacks
-export([init/1, handle_call/3, handle_cast/2, handle_info/2,
terminate/2, code_change/3]).
-define(SERVER, ?MODULE).
-record(state, { id, locked = false, requests = [] }).
%%%===================================================================
%%% API
%%%===================================================================
%% @doc Starts the server
start(Id) ->
case gen_server:start({local, ?SERVER}, ?MODULE, Id, []) of
{error,{already_started, Pid}} ->
{ok,Pid};
Else ->
Else
end.
stop(Id) ->
try
gen_server:call(?SERVER, {stop,Id})
catch exit:{noproc,_} ->
stopped
end.
request() ->
try
gen_server:call(?SERVER,{request,self()},infinity)
catch exit:{noproc,_} ->
locked
end.
release() ->
try
gen_server:call(?SERVER,{release,self()})
catch exit:{noproc,_} ->
unlocked
end.
%%%===================================================================
%%% gen_server callbacks
%%%===================================================================
%% @doc Initiates the server
init(Id) ->
{ok, #state{ id = Id }}.
%% @doc Handling call messages
handle_call({stop,Id}, _From, #state{ id = Id, requests = Reqs } = State) ->
_ = [gen_server:reply(Req, locker_stopped) || {Req,_ReqId} <- Reqs],
{stop, normal, stopped, State};
handle_call({stop,_Id}, _From, State) ->
{reply, stopped, State};
handle_call({request, Pid}, _From, #state{ locked = false,
requests = [] } = State) ->
Ref = monitor(process, Pid),
{reply, locked, State#state{ locked = {true, Pid, Ref}} };
handle_call({request, Pid}, From, #state{ requests = Reqs } = State) ->
{noreply, State#state{ requests = Reqs ++ [{From,Pid}] }};
handle_call({release, Pid}, _From, #state{ locked = {true, Pid, Ref},
requests = []} = State) ->
demonitor(Ref,[flush]),
{reply, unlocked, State#state{ locked = false }};
handle_call({release, Pid}, _From,
#state{ locked = {true, Pid, Ref},
requests = [{NextFrom,NextPid}|Rest]} = State) ->
demonitor(Ref,[flush]),
gen_server:reply(NextFrom,locked),
NextRef = monitor(process, NextPid),
{reply,unlocked,State#state{ locked = {true, NextPid, NextRef},
requests = Rest } };
handle_call({release, _Pid}, _From, State) ->
{reply, not_locked, State}.
%% @doc Handling cast messages
handle_cast(_Msg, State) ->
{noreply, State}.
%% @doc Handling all non call/cast messages
handle_info({'DOWN',Ref,process,Pid,_},
#state{ locked = {true, Pid, Ref},
requests = [{NextFrom,NextPid}|Rest] } = State) ->
gen_server:reply(NextFrom, locked),
NextRef = monitor(process, NextPid),
{noreply,State#state{ locked = {true, NextPid, NextRef},
requests = Rest } }.
%% @doc This function is called by a gen_server when it is about to terminate.
terminate(_Reason, _State) ->
ok.
%% @doc Convert process state when code is changed
code_change(_OldVsn, State, _Extra) ->
{ok, State}.
%% -------------------------------------------------------------------------
%% Internal Functions
%% -------------------------------------------------------------------------
